Systems are known to detect fires. Such systems typically include a number of fire detectors and pull stations distributed throughout a secured area (e.g., a building).
Each of the fire detectors and pull stations (devices) is typically connected to a local fire alarm panel. Upon detection of a fire, an audible and/or visual alarm connected to the panel may be activated to warn occupants of the secured area of the possibility of a fire. The alarm panel may also send an alarm message to a central monitoring station at a remote location.
In analog addressable fire systems, the alarm devices are typically connected to the panel via one or more 2-wire loops. In this regard, each of the devices may be connected in parallel across the two wires of the 2-wire loop.
The wires of the 2-wire loop include a power conductor and a neutral conductor. The power conductor provides both power and a communications channel between the panel and each of the detectors.
Included within each of the devices are a transceiver and an associated alarm device. The transceiver is used for communicating with the panel through the power conductor. The alarm device may be a fire detector or the manually activated switch of a pull station.
In this regard, each of the alarm devices is individually addressable by the panel. During normal operation, the panel may periodically poll each alarm device for status information.
While analog addressable fire systems work well, they have a limited utility in addressing changing safety criteria. For example, in old or monumental buildings or buildings where modifications are often difficult (e.g., the presence of asbestos prevents economical modifications), it is often impossible to update such systems to meet conditions. Accordingly, a need exists for better methods of utilizing 2-wire systems.